Welwitschia

Welwitschia

(Welwitschia bainesii, W. mirabilis), a gymnospermous dioecious plant of the Welwitschiaceae family. The single representative of this family grows on the infertile rocky soils of southwest Angola and in the Namib and Kalahari deserts. The long powerful roots of the welwitschia reach to the level of the ground waters. The stalk is low and thick (to 1.2 m in diameter) and columnar; its greatest part is hidden in the ground, with only a small portion (to 0.5 m) emerging above. The upper part of the stalk is more or less saddle-like or bilobate with thong-like leathery leaves (to 3 m long) along the edges of the laminae. The leaves are retained until the end of the plant’s life (100 years and more). On adult plants the leaves break into ribbon-like strips.

Within the context of the structurally diverse female gametophytes of seed plants, it has long been recognized (Coulter 1914) that some of the most anomalous seed plant female gametophytes are found in species of Gnetum, which with Welwitschia and Ephedra comprise the Gnetales.

acid phosphatase, was detected in the pollination drop of Welwitschia, it is not known whether it was secreted into the drop by nucellar tissue, or it arrived in the drop after degenerative formation of the pollen chamber.

In the coastal desert of Namibia, which can be considered a cold desert because of the humidity and the almost total lack of rain, the vegetation consists of succulent plants and acacias; in the granitic areas, spiny euphorbias, succulent members of the geranium family (Sarcocaulon), and aloes (Aloe dichotoma) are dominant; there are extensive stony areas without vegetation, and where there are sand dunes, the leaves of the very bizarre welwitschia (Welwitschia mirabilis).

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